Creating a file with $SIZE

Robert Bossy Robert.Bossy at jouy.inra.fr
Fri Mar 14 11:18:48 CET 2008


Bryan Olson wrote:
> Robert Bossy wrote:
>   
>> cokofreedom at gmail.com wrote:
>>     
>>> Robert Bossy wrote:  
>>>       
>>>> Indeed! Maybe the best choice for chunksize would be the file's buffer
>>>> size... 
>>>>         
>
> That bit strikes me as silly.
>   
The size of the chunk must be as little as possible in order to minimize 
memory consumption. However below the buffer-size, you'll end up filling 
the buffer anyway before actually writing on disk.


>> Though, as Marco Mariani mentioned, this may create a fragmented file. 
>> It may or may not be an hindrance depending on what you want to do with 
>> it, but the circumstances in which this is a problem are quite rare.
>>     
>
> Writing zeros might also create a fragmented and/or compressed file.
> Using random data, which is contrary to the stated requirement but
> usually better for stated application, will prevent compression but
> not prevent fragmentation.
>
> I'm not entirely clear on what the OP is doing. If he's testing
> network throughput just by creating this file on a remote server,
> the seek-way-past-end-then-write trick won't serve his purpose.
> Even if the filesystem has to write all the zeros, the protocols
> don't actually send those zeros.
Amen.

Cheers,
RB



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